"Three monumental masks, located over three original doorways into A-6-2nd, are
found within the lower register. The masks on both ends of the frieze seem
to be identical and may represent the World Tree or central axis of the Maya
world. The central mask, now visible only in the drawing, may represent Chac, an
important deity in the Maya creation of the world. Between the masks are two
U-shaped elements which represent the moon.

Above the central mask is a throne with an open mouthed, jawless serpent head
facing to the left. On both sides of the throne, figures can be seen holding
up the sky. Representations of the Xunantunich lineage probably were originally sculpted above the two end masks and on the central throne. A fragment of
such a portrait can be seen on the west frieze."